$ { \left[\begin{array}{rr}{-1} & {1} \\ {1} & {0} \\ {-2} & {0}\end{array}\right]+\left[\begin{array}{rr}{1} & {3} \\ {-1} & {3} \\ {-1} & {2}\end{array}\right] = {?} } $
Explanation: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{-1}+{1} & {1}+{3} \\ {1}+{-1} & {0}+{3} \\ {-2}+{-1} & {0}+{2}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{0} & {4} \\ {0} & {3} \\ {-3} & {2}\end{array}\right]}$